The vinegar essence I use has a very pungent smell. It#s not toxic but unpleasant, one reason you dilute it with water. But as the smell evaporates quickly, I usually just open the window or hold my nose.
BTW: If you' are in chalky area and have lots of limestone, put the mixed fluid onto the surface and let it sit for about 10 to 20 minutes. Then clean it up.
For cleaning and decaling your kettle you may use both the vinegar essence or citric acid. Fill the kettle at half with water and the essence/acid, heat it near boiling temperature, let it sit for a few minutes, then pour it out. Clean the kettle afterwards with water and a drop of detergent so that no residual odour remains for your teawater to attain a strange flavour.